A ball that is thrown upwards has a store of kinetic energy as it leaves the person's hand. Describe the change in energy stores as the ball rises and falls again. (Please try to be as clear as you can).

Identify the arrows that show the correct direction of heat transfer. 66°f 112°f 98°f

Abearing is designed to a reduce friction b. support a load c. guide moving parts such as wheels, shafts and pivots d. all of the above

Consider a double atwood machine constructed as follows: a mass 4m is suspended from a string that passes over a massless pulley on frictionless bearings. the other end of this string supports a second similar pulley, over which passes a second string supporting a mass of 3m at one end and m at the other. using two suitable generalized coordinates, set up the lagrangian and use the lagrange equations to find the acceleration of the mass 4m when the system is released. explain why the top pulley rotates even though it carries equal weights on each side.